Abstract: A new A site complex lead-free ferroelectric ceramics of (1-x)Bi_0.5(Na_0.82K_0.18)_0.5TiO₃-xBiCrO₃(BNKT-BCx) was prepared by a conventional solid state reaction method and dielectric properties of the system in the temperature from room temperature to 500℃ were investigated. It can be evidently seen that there are two abnormal dielectric peaks and a dielectric loss peak with increasing temperature. The dielectric constant near temperature of low abnormal peak has obvious frequency dependence, and Curie temperature shifts insignificantly with increasing frequency, which is different from the characteristics of typical relaxor ferroelectrics. It suggests that relaxor ferroelectrics can be divided into the intrinsic relaxor ferroelectrics and extrinsic relaxor ferroelectrics. The frequency dependence near the temperature of low dielectric peak is extrinsic relaxor which is created by space charges and defects dipole by using the ε_r-T curves of poled and unpoled samples.

Key words: sodium bismuth titanate, ferroelectric ceramics, dielectrics properties, relaxor characteristics